This invention relates to builders' cradles. These are used to gain access to buildings for the purpose of exterior maintenance.
Traditional builders' cradles are suspended by wires or ropes from a carriage on a rail attached to the top of a building. They are awkward to work from because they swing away from the building, (unless the cradle is the permanently fixed type with fixed vertical rails).
One known cradle is disclosed in U.S. Pat. No. 3,661,226 (Fisher), and comprises a suspended working platform which is movable up and down the side of an object to be welded by means of winches which can reel in or pay out cables by means of which the platform is suspended. The cradle is provided with guide wheels which engage with guide tracks on the object to be welded to keep the cradle moving in a straight line. The cradle is provided with two pulley wheels mounted on a horizontal axis, which are outwardly spring-loaded. Cables attached to the top and to the bottom of the object to be welded pass over a respective one of the pulleys, and are held taut by the spring-loading thereof, which therefore urge the cradle towards the object to be welded and keep it in contact therewith.
However, the use of guide wheels and the necessity for guide tracks limit the applicability of this known device. In particular, it would be very difficult to adapt the known device for use as a temporary cradle which might be necessary, for example, when restoration work is being carried out on a building. The prior art device is more suited to applications wherein the cradle is repeatedly used on the same structure, where guide tracks were provided. In the absence of guide tracks, although the cradle would still be biassed towards the object, there is nothing to prevent the cradle from moving horizontally except the vertical wires which would tend to flex. This might make the cradle difficult and/or dangerous to use on a structure which is not specifically adapted to work with the cradle, especially, for example, on a building in high winds. Additionally, there are no means for moving the cradle from side to side, only means for moving it up and down along the length of the guide tracks.